Micro valve apparatus using micro bead and method for controlling the same

ABSTRACT

A micro (thin film type) valve apparatus for controlling fluid flow and its rate using a microbead and a method for controlling the apparatus are provided. The microbead is moved by the magnetic forge generated by upper and lower electromagnets disposed on the top and bottom surface of the body or by the electric field generated by upper and lower electrode plates disposed on the top and bottom surface of the body, thereby interconnecting or blocking flow channels in the body. The micro valve apparatus and the method for controlling the same are suitable for thin film type diagnostic assay devices, such as lab-on-chips, protein chips, or DNA chips, for detecting small quantities of analytes in fluids, and more suitable for interconnecting or blocking channels formed in thin disk type apparatus including general CD-ROMs, DVDs, bioCDs, and bio DVDs.

This application is a 371 of PCT/KR02/01035 filed on May 31, 2002,published on Dec. 5, 2002 under publication number WO 02/097422 A1 whichclaims priority benefits from Korean patent application number KR2001/31284 filed May 31, 2001.

TECHNICAL FIELD

The present invention relates to the field of controlling fluid flow andits rate in a micro assay device for the detection of a small quantityof an analyte in a fluid. More particularly, the present inventionrelates to a micro (thin film type) valve apparatus using a microbead tocontrol fluid flow or its rate, and a method for controlling the microvalve apparatus.

BACKGROUND ART

To date, for most diagnostic assay apparatuses for the detection ofsmall quantities of analytes in fluids, multiple-sample preparation andautomated reagent addition devices, or multiple-sample assay apparatusesfor identifying a number of samples at the same time, either in parallelor serial procession, have been designed to improve efficiency andeconomy. Such an automated reagent preparation device and an automatedmultiple-sample assay apparatus are integrated into a single thin filmtype apparatus. This thin film type diagnostic assay apparatus canautomatically or semi-automatically accurately analyze hundreds ofanalytes using trace amounts of a sample and reagents. The thin filmtype assay apparatus needs a valve for automatically supplying a sampleor reagents (enzyme and buffer). However, designing such a valve for athin film type assay apparatus is complicated. Therefore, there is aneed to design a simple valve suitable for the thin film type assayapparatus.

<Thin Film Type CD & DVD>

The standard compact disk is formed from a 12-cm polycarbonatesubstrate, a reflective metal layer, and a protective lacquer coating.DVD stands for digital video disk, a type of optical disk of the samesize as the compact disk, but with significantly greater recordingcapacity.

The polycarbonate substrate is optical-quality clear polycarbonate. In astandard pressed CD or DVD, the data layer is part of the polycarbonatesubstrate, and the data are impressed as a series of pits by a stamperduring injection molding. In the injection molding process, meltedpolycarbonate is injected into a mold under high pressure and cooled ina mirror image of the mold or stamper. As a result, reverse pits of thestamper are formed on the polycarbonate disk surface during mastering asbinary data. The stamping master is typically glass.

Those disks can be modified into CD-ROMs, DVDs, bio-CDs or bio-DVDs asthin disk type diagnostic assay apparatuses for detecting non-biologicalanalytes or biological molecules in a fluid. In this case, duringinjection molding, instead of the pits, channels as fluid flow paths andchambers as buffer reservoirs can be formed in the disk surface.Additionally, a thin film type valve for controlling fluid flow and itsrate through the channels formed in the thin disk surface is required.

GB 1075800 (published Jul. 12, 1967), entitled “Disc for Centrifuge”,disclosures a device for flowing a sample fluid supplied via an injecthole of the disc over the surface of the disc by centrifugal force. EP3335946 (published Apr. 12, 1965), entitled “Separating Disks forCentrifuge”, discloses an apparatus for separating fluid samplesinjected via an inject hole of the disc by flowing the samples throughchannels or chambers formed in the disc. However, these apparatusesfailed to overcome the problems of the thin film type valve and toprecisely control flow rate.

A general valve using an electromagnet opens or closes a flow path usinga cylinder or a plunger that is moved by magnetic force. To intensifythe magnetic force so as to move the cylinder or flange, a ferroelectriccore of an appropriate size and a number of wires wound around the coreare required. Also, a large amount of electricity is required to turn onor off the valve and move the cylinder or flange. The valve using theelectromagnet cannot be constructed as a thin film type valve due to thesize of the electromagnet. The valve generates excess heat by consuminga large amount of electricity. To address these problems, according tothe present invention, electromagnets and a microbead are used. A valveusing the microbead according to the present invention can beconstructed in thin film form, and a small force is required to move themicrobead. Accordingly, the electromagnets can be formed as thin films.Also, since electricity consumption is very low, no heat is generatedwhen the valve is operated.

Therefore, the micro (thin film type) valve apparatus and the method forcontrolling the same according to the present invention are suitable fora thin film type diagnostic assay apparatus, such as a lab-on-a-chip, orDNA-chip, for detecting a small quantity of an analyte in a fluid, andespecially, for interconnecting and blocking channels formed in a thindisk type assay device, such as a CD-ROM, a DVD, a bio-CD, and abio-DVD, or for controlling the rate of fluid flowing.

Accordingly, it is an object of the present invention is to provide amicro (thin film type) valve apparatus and a method for controlling thesame, in which a microbead that is moved by the magnetic or electricforce generated by electromagnets or electrode plates installed on thetop and bottom surfaces of its body is placed in the middle of channelsto block or interconnect the channels.

It is another object of the present invention to provide a thin filmtype diagnostic assay apparatus for detecting a small quantity of ananalyte using the micro (thin film type) valve apparatus for controllingfluid flow and its rate, and particularly, to provide an nucleic acidassay apparatus and method for detecting whether a sample contains atarget nucleic acid or not, using the micro (thin film type) valveapparatus.

DISCLOSURE OF THE INVENTION

In one aspect, the present invention provides a micro valve apparatuscomprising: channels as flow paths of a fluid; a hole whichinterconnects the channels; a thin disk type body in which the channelsand the hole are formed; upper and lower electromagnets mounted on thetop and bottom surfaces of the body, respectively, opposite to eachother, which generate a magnetic force with the application of power;and a microbead which is moved upward or downward by on/off control ofthe power applied to the upper and lower electromagnets, to open andclose the hole, thereby controlling fluid flow and its rate.

Alternatively, the present invention provides a micro valve apparatuscomprising: channels as flow paths of a fluid; a hole whichinterconnects the channels; a thin disk type body in which the channelsand the hole are formed; upper and lower electrode plates mounted on thetop and bottom surfaces of the body, respectively, opposite to eachother, which generate an electric field with the application of power;and a charged microbead which is moved upward or downward by controllingthe direction in which power is applied to the upper and lower electrodeplates, to open and close the hole, thereby controlling fluid flow andits rate.

In each of the micro valve apparatuses described above, the body maycomprise a ventilating hole through which air is exhausted to allowsmooth flow of the fluid. In this case, the ventilating hole is formedin an opposite direction to the direction in which the fluid flows or acentrifugal force is exerted.

In each of the micro valve apparatuses described above, the body may beformed of a material selected from the group consisting of plastic,polymethylmethacrylate (PMMA), glass, mica, and silica. Preferably, themicrobead is formed of a material selected from the group consisting offerroelectric particles, paramagnetic particles, diamagnetic particles,metal particles, metal-coated plastic particles, and metal-coated glassparticles. Preferably, the microbead is spherical or non-spherical, andmore preferably, spherical. Preferably, the non-spherical microbead is athin cylindrical element or a thin rectangular element.

Preferably, the microbead has a diameter of 1 μm-1 mm, and morepreferably, 100-500 μm. Preferably, the hole is rounded corresponding toa curvature of the microbead. Preferably, the hole includes an auxiliaryinner hole having a diameter smaller than the microbead and/or anauxiliary outer hole having a diameter greater than the microbead.

In each of the micro valve apparatuses described above, the body may bea thin disk type apparatus selected from the group consisting of CD-ROM,DVD, bio-CD, and bio-DVD. Preferably, the body comprises a confininggroove and/or a confining channel which holds the microbead and preventsit from leaving away.

Preferably, the body is constructed by binding upper, intermediate, andlower substrates together. In this case, two chambers and the hole areformed through the intermediate substrate, one chamber and an upperchannel connecting the chamber and the hole are formed recessed to adepth in the upper substrate, and the other chamber and a lower channelconnecting the chamber and the hole are formed recessed to a depth inthe lower substrate.

In another aspect, the present invention provides a method forcontrolling the micro valve apparatus described above, which includesthe upper and lower electromagnets, the method comprising: in order toblock the channels by closing the hole of the micro valve apparatus,cutting off the power applied to the upper electromagnet and applyingpower to the lower electromagnet to attract the microbead to the hole;and in order to interconnect the channels with each other by opening thehole, cutting off the power applied to the lower electromagnet andapplying power to the upper electromagnet to attract the microbead so asto be removed from the hole.

Alternatively, the present invention provides a method for controllingthe micro valve apparatus described above, which includes the upper andlower electrode plates, the method comprising: in order to block thechannels by closing the hole of the micro valve apparatus, applying avoltage of the same polarity as the charge of the microbead to the upperelectrode plate to repel the charged microbead and applying a voltage ofthe opposite polarity to the lower electrode plate to attract thecharged microbead to the hole; and in order to interconnect the channelswith each other by opening the hole, applying a voltage of the samepolarity as the charge of the microbead to the lower electrode plate torepel the charged microbead and applying a voltage of the oppositepolarity to the upper electrode plate to attract the charged microbeadso as to be removed from the hole.

In another aspect, the present invention provides a nucleic acid assaydevice in which fluid flow between chambers is controlled by one of themicro valve apparatuses described above, the device comprising: a sampleinjection unit via which a nucleic acid containing sample is injected; apreparation chamber where DNAs or RNAs are prepared from the nucleicacid containing sample; a PCR (polymerase chain reaction) chamber wherethe DNAs or RNAs are amplified through PCR or RT-PCR; an array chamberwhere the amplified DNAs or cDNAs are hybridized to a capture probe; atrash chamber where the non-hybridized waste from the array chamber iscollected; and a plurality of chambers for storing a variety of enzymesand buffer solutions required for processes.

Preferably, the nucleic acid assay device is a lab-on-a-chip where thepreparation chamber, the PCR chamber, the trash chamber, channels, andholes are formed in a disk type body. In this case, the disk type bodymay be constructed by binding the upper, intermediate, and lowersubstrates together.

In the nucleic acid assay device according to the present invention, itis preferable that opening or closing of the holes of the micro valveapparatus at the start and end of each of the processes is controlled byon/off control of the power applied to the upper and lowerelectromagnets or by controlling the direction in which power is appliedto the upper and lower electrode plates, and that the fluid flow isinduced by the centrifugal force which occurs as the disk type body isrotated.

In anther aspect, the present invention provides a nucleic acid assaymethod in the nucleic acid assay device described above, the methodcomprising: (a) injecting a nucleic acid containing sample into thepreparation chamber via the sample injection unit; (b) preparing DNAs orRNAs from the nucleic acid containing sample; (c) opening a first holebetween the preparation chamber and the PCR chamber and rotating thenucleic acid assay device for a predetermined period of time, totransfer the prepared DNAs or RNAs to the PCR chamber; (d) closing thefirst hole, opening a second hole between a chamber which store enzymesand buffer solutions required for PCR and the PCR chamber, andperforming the PCR or RT-PCR to amplify the DNAs or RNAs; (e) after thePCR or RT-PCR has completed, closing the second hole, opening a thirdhole between the PCR chamber and the array chamber, and rotating thenucleic acid assay device for a predetermined period of time, totransfer the amplified DNAs or dDNAs to the array chamber; (f) closingthe third hole, opening a fourth hole between a chamber which storesenzymes and buffer solutions required for hybridization and the arraychamber, and performing the hybridization; and (g) after thehybridization has completed, closing the fourth hole, opening a fifthhole between the array chamber and the trash chamber, and rotating thenucleic acid assay device for a predetermined period of time, to collectthe waste from the hybridization within the trash chamber.

The present invention will be described in greater detail with referenceto the appended drawings.

Referring to FIGS. 1A and 1B, a body 100 or solid substrates 1, 2, and 3can be formed of a variety of materials, including plastic,polymethylmethacrylate (PMMA), glass, mica, silica, etc. However, amongthose materials, plastic is most preferred for economical reasons,convenience of processing, and compatibility with existing laserreflection-based detectors for CD-ROMs and DVDs. Suitable plasticsinclude polypropylenes, polyacrylates, polyvinyl alcohols,polyethylenes, polymethylmethacrylates, and polycarbonates. Among thosematerials, polypropylenes and polycarbonates are more preferred, withpolycarbonates being most preferred.

In an embodiment according to the present invention, the microbeadincludes, for examples, ferroelectric particles, paramagnetic particles,diamagnetic particles, metal particles, etc. The microbead can be formedof plastic or glass particles, which is further coated with a metal.Alternatively, the metal particles for the metal bead can be metal-alloyparticles. The microbead can be charged. In this case, instead ofelectromagnets, electrode plates are arranged on the top and bottomsurfaces of the body 100. The charged microbead can be moved accordingto the direction in which a voltage is applied to the electrode plates,to open or close a hole connecting channels.

The microbead has a diameter of 1 μm-1 mm, and preferably, 100 μm-500μm. When the diameter of the microbead is increased, the hole can beopened or plugged with higher reliability due to an increase in thecontact area between the hole and the microbead.

Microbeads suitable for use in the valve apparatus according to thepresent invention are readily available in varying diameters fromAldrich Chemical Company, British BioCell International, Nanoprobes,Inc. It will be appreciated by those skilled in the art that thediameter of the microbead can be increased or reduced as needed.

The micro (thin film type) valve apparatus according to the presentinvention includes a body 100 having an inlet 11 a, an outlet 11 b,channels 22, and a ventilating hole 12, electromagnets 4 a and 4 bmounted on the opposite surfaces of the body 100 to generate a magneticforce with the application of power, a hole 10 connecting the channels22 in the body 100, and a microbead 70 that is moved upward or downwardby the magnetic force generated by the electromagnets 4 a and 4 b toopen or close the hole 10, thereby controlling fluid flow and its rate.

In the present invention, preferably, the electromagnets 4 a and 4 b arethin electromagnets with an air core. As described above, the microbead70 can be a magnetic ball, a thin cylindrical magnet, or thinrectangular magnet (bar magnet). As power is applied to theelectromagnets 4 a or 4 b, the spherical magnet, thin cylindricalmagnet, or thin rectangular magnet is attracted to the electromagnets 4a or 4 b.

FIGS. 1A and 1B are sectional views for illustrating the operation ofthe micro (thin film type) valve apparatus using the microbead accordingto the present invention. Reference numerals 1, 2, and 3 denote threesubstrates constituting the body 100.

The body 100 is constituted by the upper substrate 1, the intermediatesubstrate 2, and the lower substrate 3. While the upper substrate 1, theintermediate substrate 2, and the lower substrate 3 are formed byinjection molding, the channels 22 as flow paths, chambers 20 and 22 asbuffer reservoirs, and the hole 10 connecting the channels 22 areformed. The upper substrate 1, the intermediate substrate 2, and thelower substrate 3 are bound together to form a single body 100.

FIG. 1A illustrates the state where the hole 10 is plugged by themicrobead 70 to block the channels 22, and FIG. 1B illustrates the satewhere the microbead 70 is removed from the hole 10 to interconnect thechannels 22 with each other. To block the channels 22 by plugging thehole 10 with the microbead 70, as shown in FIG. 1A, power is applied tothe lower electromagnet 4 b while the power applied to the upperelectromagnet 4 a disposed opposite to the lower electromagnet 4 b iscut off. To interconnect the channels 22 by opening the hole 10, asshown in FIG. 1B, power is applied to the upper electromagnet 4 a whilethe power applied to the lower electromagnet 1 b is cut off.

According to the present invention, since the channels 22 formed in thethin film type body 100 are narrow, the ventilating hole 12 is formed inthe upper substrate 1 to reduce the air pressure and allow a fluid tosmoothly flow through the channels 22.

Also, a confining groove 101 is formed in the upper substrate 1 toreceive the microbead 70 when the channels 22 are interconnected witheach other, as shown in FIG. 1B. The confining groove 101 holds themicrobead 70 and prevents the microbead 70 from dropping into andplugging the hole 10 when the body 100 shakes. Preferably, the curvatureof the confining groove 101 is about 50-70% greater than that of themicrobead 70.

FIGS. 2A, 2B, 2C, and 2D illustrate a variety of embodiments of the hole10 in the micro valve apparatus using the microbead 70 according to thepresent invention. Reference numeral 10 denotes a contact region betweenthe microbead 70 and the intermediate substrate 2. The contact region isrounded corresponding to the curvature of the microbead 70 to prevent aleakage of the fluid when the hole 10 is plugged by the microbead 70.

Reference numeral 10 a denotes the outer margin (also referred to as“outer hole”), and reference numeral 10 b denotes the inner margin (alsoreferred to as “inner hole”) of the contact region. When the contactregion is larger, the leakage of the fluid can be more effectivelyprevented. Preferably, the contact region has a diameter of 100-500 μm.

FIG. 2B illustrates another embodiment of the hole 10 where the innerhole 10 b has an auxiliary inner hole 19 b. This structure with theauxiliary inner hole 19 b is suitable when a thickness of theintermediate substrate 2 is greater than the radius of the microbead 70.FIG. 2C illustrates another embodiment of the hole 10 where the outerhole 10 a and the inner hole 10 b have respective auxiliary holes 19 aand 19 b. When the channels 22 a and 22 c are interconnected with eachother, due to the auxiliary outer hole 19 a, the distance by which themicrobead 70 is moved above to open the hole 12 can be reduced.

FIG. 2B illustrates another embodiment of the hole 10 in the micro valveapparatus according to the present invention when a thin cylindricalelement or a thin rectangular element is used as the microbead 70′.Reference numeral 10 denotes a contact region between the thincylindrical or rectangular element 70′ and the intermediate substrate 2.Reference numeral 10 a denotes the outer margin (“outer hole”) of thecontact region, and reference numeral 10 b denotes the inner margin(“inner hole”) of the contact region. A confining groove 101′ is formedin the upper substrate 1 to receive the thin cylindrical or rectangularelement 70′ when the channels 22 a and 22 c are interconnected with eachother. The confining groove 101′ holds the thin cylindrical orrectangular element 70′ and prevents it from dropping into and pluggingthe hole 10 when the body 100 shakes.

FIGS. 3A, 3B, and 3C illustrate the upper substrate 1, the intermediatesubstrate 2, and the lower substrate 3, respectively, of the micro (thinfilm type) valve apparatus using the microbead according to the presentinvention, where the channels 22, the hole 10, and the chambers 20 and21, which are described above, are formed. The upper substrate 1, theintermediate substrate 2, and the lower substrate 3 are bound togetherto form a single body 100. Although not illustrated in FIGS. 3A, 3B, and3C, the inlet is formed on the left, and the outlet is formed on theright. In FIGS. 3A, 3B, and 3C, the filled-in elements (black) areformed through the substrate, and the other elements (white) are formedrecessed to a depth in the substrate.

As the upper substrate 1, the intermediate substrate 2, and the lowersubstrate 3 are bound together, the elements 20 a, 20 b, 20 c form thechamber 20 near the inlet, and the elements 21 a, 21 b, and 21 c formthe chamber 21 near the outlet. In FIG. 3A, reference numeral 22 adenotes an upper channel connected to an outlet of the chamber 20 aformed in the upper substrate 1. In FIG. 3C, reference numeral 22 cdenotes a lower channel connected to an inlet of the chamber 21 c formedin the lower substrate 3. In FIG. 3B, reference numeral 10 denotes thehole whose wall is rounded to fit to the microbead 70.

At one end of the upper and lower channels 22 a and 22 c, respectiveupper and lower confining channels 23 a and 23 c are formed. The upperand lower confining channels 23 a and 23 c have a diameter that is alittle greater than the microbead 70 to prevent the microbead 70 fromleaving away when the body 100 shakes. As the upper substrate 1, theintermediate substrate 2, and the lower substrate 3 are bound togetherto form the body 100, the upper confining channel 23 a, the hole 10, andthe lower confining channel 23 c are interconnected with one another toform a single hole unit. The hole is opened or plugged by the microbead70 that is moved by the magnetic force generated by the upper and lowerelectromagnets 4 a and 4 b. To prevent the microbead 70 from leavingaway, the upper and lower confining channels 23 a and 23 c have adiameter that is preferably 30-60% greater than the microbead 70.

FIGS. 3A and 3D are bottom and top views of the upper substrate 1,respectively. In the top view of FIG. 3D, the ventilating hole 12 isapparent. In the micro valve apparatus according to the presentinvention, a fluid flows by centrifugal force or external pressure. Toprevent the fluid from entering the ventilation hole 12, a ventilatingpath 24 connected to the ventilating hole 12 is formed toward the inletof the body 100, i.e., opposite to the direction in which thecentrifugal force is exerted.

In another aspect of the present invention, there is provided a methodfor controlling fluid flow and its rate in the micro (thin film type)valve apparatus using the microbead, by controlling the duration of timein which the hole is opened or closed by the microbead that is moved bythe magnetic force generated by the upper or lower electromagnets

In the method for controlling the micro valve apparatus using themicrobead according to the present invention, to block fluid flowthrough the channels 20 and 21 in the micro valve apparatus, the powerapplied to the upper electromagnet 4 a is cut off, and power is appliedto the lower magnet 4 b to attract the microbead 70 to the hole 10,thereby plugging the hole 10. In contrast, to interconnect the channels20 and 21 with each other to allow fluid flow, the power applied to thelower electromagnet 4 b is cut off, and power is applied to the upperelectromagnet 4 a to pull the microbead 70 so as to be removed from thehole 10.

In another aspect of the present invention, there is provided a methodfor controlling fluid flow and its rate in a micro valve apparatus usinga charged microbead, in which the charged microbead is moved using acharged microbead, in which the charged microbead is moved by anelectric field generated by upper and lower electrode plates 4 a′ and 4b′ of the body, to open or close the hole, thereby controlling fluidflow and its rate. In this embodiment, the upper and lowerelectromagnets 4 a and 4 b used in the previous embodiment are replacedby the upper and lower electrode plates 4 a′ and 4 b′.

With the assumption that a positively charged microbead is used, theoperation for controlling the micro valve apparatus to open or close thehole 10 will be described. To block fluid flow through the channels 20and 21, a positive voltage is applied to the upper electrode plate 4 a′to repel the positively charged microbead 70 and move it toward the hole10, and a negative voltage is applied to the lower electrode plate 4 b′to attract the positively charged microbead to the hole 10, therebyplugging the hole 10. In contrast, to interconnect the channels 20 and21 with each other to allow fluid flow, a negative voltage is applied tothe upper electrode plate 4 a′ to attract the positively chargemicrobead 70 so as to be removed from the hole 10, and a positivevoltage is applied to the lower electrode plate 4 b′ opposite to theupper electrode plate 4 a′ to increase the rate of fluid flowing throughthe hole 10.

BRIEF DESCRIPTION OF THE DRAWINGS

FIGS. 1A and 1B are sectional views for illustrating the states where amicro valve apparatus using a microbead according to the presentinvention operate;

FIGS. 2A, 2B, 2C, and 2D illustrate a variety of embodiments of a holein the micro valve apparatus using the microbead according to thepresent invention;

FIGS. 3A, 3B, 3C, and 3D illustrate upper, intermediate, and lowersubstrates of the micro valve apparatus using the microbead according tothe present invention, where channels, a hole, chambers, a ventilatinghole are formed;

FIG. 4 shows an embodiment of the micro valve apparatus using themicrobead according to the present invention applied to a thin disk typelab-on-a-chip, such as a general CD-ROM, DVD, bio-CD, or bio-DVD;

FIGS. 5A and 5B are top and bottom views of the upper substrate as aconstituent of the body of the micro valve apparatus using the microbeadaccording to the present invention, respectively, where channels, holes,chambers, and upper electromagnets are formed;

FIGS. 6A and 6B are top and bottom views of the intermediate substrateas a constituent of the body of the micro valve apparatus using themicrobead according to the present invention, respectively, where holesand channels are formed;

FIGS. 7A and 7B are top and bottom views of the lower substrate as aconstituent of the body of the micro valve apparatus using the microbeadaccording to the present invention, respectively, where channels, holes,chambers, and lower electromagnets are formed; and

FIG. 8 is a flowchart for illustrating a method for controlling a microvalve apparatus using a microbead according to an embodiment of thepresent invention in a thin disk type lab-on-a-chip, such as a generalCD-ROM, DVD, bio-CD, or bio-DVD.

BEST MODE FOR CARRYING OUT THE INVENTION

The present invention will be described in greater detail with referenceto the following embodiments. The following embodiments are forillustrative purposes and are not intended to limit the scope of theinvention.

<Nucleic Acid Assay Device>

FIG. 4 shows a plan view and a sectional view, taken along line a-b, ofan nucleic acid assay device constructed as a lab-on-a-chip according toan embodiment of the present invention, where the micro valve apparatususing a microbead according to the present invention is installed in athin disk type apparatus 200. The thin disk type apparatus 200 may be ageneral CD-ROM, DVD, bio-CD, or bio-DVD.

Reference numeral 100 denotes a body constructed by binding the uppersubstrate 1, the intermediate substrate 2, and the lower substrate 3together. Microbeads 70 a, 70 b, and 70 c are independently moved by themagnetic force generated by electromagnetic pairs 190 a 190 b, 191 a and191 b, and 192 a and 192 b, respectively, to open or close holes.Reference numeral 120 denotes a pipette or syringe for sample injection,reference numeral 121 denotes a sample inlet, and reference numeral 170denotes a disk hole.

An example of the arrangement of chambers for storing a variety of assaybuffers and for chemical reactions, channels along which sample fluidsand the buffers flow, and valves for controlling the channels to beblocked or interconnected with each other, in the thin disk typeapparatus is shown in FIG. 4.

In FIG. 4, reference numeral 130 denotes a preparation chamber where aDNA or RNA sample is prepared from blood or cells. Reference numeral 131denotes a polymerase chain reaction (PCR) chamber where PCR or RT-PCRtakes place, reference numeral 132 denotes an array chamber where theamplified DNA or cDNA fragments are hybridized to capture probesspecific for a target DNA, which are immobilized on a substrate as anarray. Reference numeral 133 denotes a trash chamber for collectingwaste generated through a wash process. Reference numeral 140 denotes achamber for storing a buffer solution including polymerases, used forthe PCR in the PCR chamber 131. Reference numerals 141, 142, and 143denote chambers for storing a variety of enzymes and buffers used forthe hybridization in the array chamber 132.

Opening and closing of the valves (holes) at the start and end of eachof the processes (preparation, PCR, hybridization, and washing process)is controlled by on/off control of the power applied to theelectromagnet pair arranged above and below each of the microbeads.Fluid flow in the apparatus is induced by the centrifugal force whichoccurs as the disk type apparatus 200 is rotated.

FIGS. 5A and 5B are top and bottom views of the upper substrate 1 as aconstituent of the body 100 of the micro valve apparatus using themicrobead according to the present invention, respectively, wherechannels, holes, chambers, and upper electromagnets are formed. FIGS. 6Aand 6B are top and bottom views of the intermediate substrate 2 as aconstituent of the body 100 of the micro valve apparatus using themicrobead according to the present invention, respectively, where holesand channels are formed. FIGS. 7A and 7B are top and bottom views of thelower substrate 2 as a constituent of the body 100 of the micro valveapparatus using the microbead according to the present invention,respectively, where channels, holes, chambers, and lower electromagnetsare formed. In FIGS. 5A, 5B, 6A, 6B, 7A, and 7B, the filled-in elementsare formed through the corresponding substrate, and the other elementsare formed recessed to a depth in the corresponding substrate. The uppersubstrate 1, the intermediate substrate 2, and the lower substrate 3 arebound together to form a single body 100.

As the upper substrate 1, the intermediate substrate 2, and the lowersubstrate 3 are bound together, the elements 130 a, 130 b, and 130 cform the preparation chamber 130, the elements 131 a, 131 b, and 131 cform the PCR chamber 131, the elements 132 a, 132 b, and 132 c form thearray chamber 132, and the elements 133 a, 133 b, and 133 c form thetrash chamber 133. The elements 140 a, 140 b, and 140 c form the chamber140 for storing a variety of enzymes and buffer use for PCR. Theelements 141 a, 141 b, and 141 c form the chamber 141, the elements 142a, 142 b, and 142 c form the chamber 142, and the elements 143 a, 143 b,and 143 c form the chamber 143, which store a variety of enzymes andbuffers used for hybridization.

In FIG. 5B, reference numeral 150 a denotes an upper channel connectedto an outlet of the preparation chamber 130 a which is formed in theupper substrate 1301, reference numeral 151 a denotes an upper channelconnected to an outlet of the PCR chamber 131 a which is formed in theupper substrate 1, and reference numeral 152 a denotes an upper channelconnected to an output let of the array chamber 132 a which is formed inthe upper substrate 1. Reference numeral 153 a denotes an upper channelconnected to an outlet of the chamber 140 a which is formed in the uppersubstrate 1, reference numeral 154 a denotes an upper channel connectedto an outlet of the chamber 141 which is formed in the upper substrate1, reference numeral 155 a denotes an upper channel connected to anoutlet of the chamber 142 a which is formed in the upper substrate 1,and reference numeral 156 a denotes an upper channel connected to anoutlet of the chamber 143 a which is formed in the upper substrate 1.Reference numerals 211 a, 211 b, and 211 c denote ventilating pathsconnected to the PCR chamber 131, the array chamber 132, and the trashchamber 133, respectively.

In FIG. 5A, upper electromagnets 1901, 191 a, 192 a, 193 a, 194 a, 195a, and 196 a mounted on the top of the upper substrate 1, andventilating holes 210 a, 210 b, and 210 c connected to the ventilatingpaths 211 a, 211 b, and 211 c, respectively, are shown.

In FIG. 7A, reference numeral 150 c denotes a lower channel connected toan inlet of the PCR chamber 131 c which is formed in the lower substrate3, reference numeral 151 c denotes a lower channel connected to an inletof the array chamber 132 c which is formed in the lower substrate 3,reference numeral 152 c denotes a lower channel connected to an inlet ofthe trash chamber 133 c which is formed in the lower substrate 3, andreference numeral 153 c denotes a lower channel connected to an inlet ofthe PCR chamber 131 c which is formed in the lower substrate 3.Reference numerals 154 c, 155 c, and 156 c denote lower channelsconnected to inlets of the array chamber 132 c which is formed in thelower substrate 3, respectively.

At one end of the upper channels 150 a, 151 a, 152 a, 153 a, 154 a, 155a, and 156 a, upper confining channels 160 a, 161 a, 162 a, 163 a, 164a, 165 a, and 166 a each of which has a predetermined diameter areformed, respectively. At one end of the lower channels 150 c, 151 c, 152c, 153 c, 154 c, 155 c, and 156 c, lower confining channels 160 c, 161c, 162 c, 163 c, 164 c, 165 c, and 166 c each of which has apredetermined diameter are formed, respectively. As the upper substrate1, the intermediate substrate 2, and the lower substrate 3 are boundtogether to form a single body 100, the upper confining channels 160 a,161 a, 162 a, 163 a, 164 a, 165 a, and 166 a, holes 160 b, 161 b, 162 b,163 b, 164 b, 165 b, and 166 b, and the lower confining channels 160 c,161 c, 162 c, 163 c, 164 c, 165 c, and 166 c are interconnected,respectively, thereby resulting in individual hole units. The holes 160b, 161 b, 162 b, 163 b, 164 b, 165 b, and 166 b are independently openedor closed by microbeads that are moved by the electromagnetic forcegenerated by corresponding upper and lower electromagnet pairs 190 a and190 b, 191 a and 191 b, 192 a and 192 b, 193 a and 193 b, 194 a and 194b, 195 a and 195 b, and 196 a and 196 b, wherein the upper and lowerelectromagnet pairs are disposed on the top surface of the uppersubstrate and the bottom surface of the lower substrate, respectively,opposite to each other with a hole therebetween. To prevent themicrobeads from dropping into and plugging the holes, it is preferablethat the confining grooves have a diameter that is 30-60% greater thanthat of the microbeads.

FIG. 8 is a flowchart for illustrating a method for controlling a microvalve apparatus using a microbead according to the present invention ina lab-on-a-chip in which a thin disk type apparatus 200 is installed.The thin disk type apparatus 200 may be a general CD-ROM, DVD, bio-CD,or bio-DVD.

Opening and closing of the valves (holes) at the start and end of eachof the processes (preparation, PCR, hybridization, and washing process)is controlled by on/off control of the power applied to theelectromagnet pair arranged above and below each of the microbeads.Fluid flow in the apparatus is induced by the centrifugal force whichoccurs as the disk type apparatus 200 is rotated.

A crude blood or cellular sample is injected into the preparationchamber 130 via the sample inlet 121 (see FIG. 4) (Step 501). In thepreparation step (Step 502), a DNA or RNA sample is extracted from thecrude blood or cellular sample. After the preparation step, the hole 160b is opened, and the disk type apparatus is rotated for a predeterminedperiod of time to generate a centrifugal force and stopped (Steps 503,504, and 555), thereby transferring the extracted DNA or RNA sample intothe RCR chamber 131. Next, the hole 160 b is closed, and the hole 163 bis opened to supply enzymes and buffer solutions required for PCR (Step506), and the PCR is performed (Step 507). In the PCR, an additionalthermal controller for thermal cycles is needed. A detailed descriptionon the thermal controller is omitted here because the present inventiondirects to the micro valve apparatus. After the PCR, to carry the DNAsample to the array chamber 132, the hole 163 is closed, the hole 161 bis opened, and the disk type apparatus 200 is rotated for apredetermined period of time and stopped (Steps 508, 509, and 510).Next, the hole 161 b is closed, and holes 164 b, 165 b, and 166 b areopened to supply enzymes and buffer solutions required for hybridization(Step 511), and the hybridization is performed (Step 512). The holes 164b, 165 b, and 166 b are closed (Step 513). Next, the hole 162 b isopened, the disk type apparatus 200 is rotated for a predeterminedperiod of time and stopped (Steps 514, 515, and 516), to collect thewaste produced during the array process in the trash chamber 133.Finally, the hole 162 b is closed (Step 517).

INDUSTRIAL APPLICABILITY

As described above, in the micro valve apparatus using microbeads orcharged microbeads according to the present invention and the method forcontrolling the same, the microbeads or charged microbeads are movedupward or downward by the electromagnetic force generated by on-offcontrol of the electromagnets or by the electric field generated bycontrolling the direction in which a voltage is applied to the electrodeplates, so that channels are opened or closed, and the flow rate iscontrolled. The micro valve apparatus and the method for controlling thesame according to the present invention are suitable for thin film typediagnostic assay devices, such as lab-on-a-chips, protein chips, or DNAchips, for detecting small quantities of analytes in fluids, and moresuitable for interconnecting or blocking channels formed in thin disktype apparatus, including general CD-ROMs, DVDs, bio-CDs, and bio-DVDs.

1. A micro valve apparatus comprising: an upper substrate; anintermediate substrate; a lower substrate; channels as flow paths of afluid, the channels formed between the upper and lower substrates; avalve hole which interconnects the channels; the valve hole formed inthe intermediate substrate, wherein the valve hole includes a firstdiameter and a second diameter, the second diameter having a diametergreater than that of the first diameter; wherein the second diameterincludes an third diameter having a diameter greater than the microbead;wherein a surface formed between the first diameter and the seconddiameter provides a contact region on the microbead for enhancingsealing of the valve hole; chambers for storing a variety of assaybuffer and for chemical reactions; the chambers formed between the upperand lower substrates; a rotatable disk in which the channels, thechambers and the valve hole are formed; wherein the fluid in thechannels flows from the center to edges of the rotatable disk bycentrifugal force caused by the rotation of the rotatable disk; upperand lower electromagnets mounted on the top and bottom of exteriorsurfaces of the rotatable disk, respectively, opposite to each other;and a microbead which is moved upward or downward by the upper and lowerelectromagnets, to open and close the valve hole, thereby controllingfluid flow or quantity, wherein an upper channel connecting a firstchamber to the valve hole is formed recessed to a first depth in theupper substrate, and a lower channel connecting a second chamber to thevalve hole is formed recessed to a second depth in the lower substrate,wherein the first and the second chambers are interconnected with eachother through the channels when the valve hole is opened, wherein theupper substrate has a confining groove which holds the microbead andprevents it from moving away when the rotatable disk rotates.
 2. A microvalve: apparatus comprising: an upper substrate; an intermediatesubstrate; a lower substrate; channels as flow paths of a fluid; thechannels formed between the upper and lower substrates; a valve holewhich interconnects the channels; the valve hole formed in theintermediate substrate chambers for storing a variety of assay bufferand for chemical reactions; the chambers formed between the upper andlower substrates; a rotatable disk body in which the channels, thechambers and the valve hole are formed; wherein the fluid in thechannels flows from the center to edges of the rotatable disk bycentrifugal force caused by the rotation of the rotatable disk; upperand lower electrode plates mounted on the top and bottom of exteriorsurfaces of the rotatable disk, respectively, opposite to each other,which generate an electric field with the application of power; and acharged microbead which is moved upward or downward by controlling thedirection in which power is applied to the upper and lower electrodeplates, to open and close the valve hole, thereby controlling fluid flowand its flux or quantity, wherein an upper channel connecting a firstchamber to the valve hole is formed recessed to a first depth in theupper substrate, and a lower channel connecting a second chamber to thevalve hole is formed recessed to a second depth in the lower substrate,wherein the first and the second chambers are interconnected with eachother through the channels when the valve hole is opened, wherein theupper substrate has a confining groove which holds the microbead andprevents it from moving away when the rotatable disk rotates.
 3. Themicro valve apparatus of claim 1 or 2, wherein the body comprises aventilating hole through which air is exhausted to allow smooth flow ofthe fluid.
 4. The micro valve apparatus of claim 3, wherein theventilating hole is formed in an opposite direction to the direction inwhich the fluid flows or a centrifugal force is exerted.
 5. The microvalve apparatus of claim 1 or 2, wherein the body is formed of amaterial selected from the group consisting of plastic,polymethylmethacrylate (PMMA), glass, mica, and silica.
 6. The microvalve apparatus of claim 1 or 2, wherein the microbead is formed of amaterial selected from the group consisting of ferroelectric particles,paramagnetic particles, magnetic particles, diamagnetic particles, metalparticles, metal-coated plastic particles and metal-coated glassparticles.
 7. The micro valve apparatus of claim 1 or 2, wherein themicrobead has a diameter of 1 μm-1 mm.
 8. The micro valve apparatus ofclaim 1 or 2, wherein the valve hole is rounded corresponding to acurvature of the microbead.
 9. The micro valve apparatus of claim 1,wherein the valve hole includes an fourth diameter having a diametersmaller than the microbead.
 10. The micro valve apparatus of claim 1,wherein each of the upper and lower electromagnets is a thinelectromagnet with an air core.
 11. A method for controlling the microvalve apparatus of claim 1, the method comprising: in order to block thechannels by closing the hole of the micro valve apparatus, cutting offthe power applied to the upper electromagnet and applying power to thelower electromagnet to attract the microbead to the hole; and in orderto interconnect the channels with each other by opening the hole,cutting off the power applied to the lower electromagnet and applyingpower to the upper electromagnet to attract the microbead so as to beremoved from the hole.
 12. A method for controlling the micro valveapparatus of claim 2, the method comprising: in order to block thechannels by closing the hole of the micro valve apparatus, applying avoltage of the same polarity as the charge of the microbead to the upperelectrode plate to repel the charged microbead and applying a voltage ofthe opposite polarity to the lower electrode plate to attract thecharged microbead to the hole; and in order to interconnect the channelswith each other by opening the hole, applying a voltage of the samepolarity as the charge of the microbead to the lower electrode plate torepel the charged microbead and applying a voltage of the oppositepolarity to the upper electrode plate to attract the charged microbeadso as to be removed from the hole.
 13. A nucleic acid assay device inwhich fluid flow between chambers is controlled by a micro valveapparatus of claim 1 or 2, the device comprising: a sample injectionunit via which a nucleic acid containing sample is injected; apreparation chamber where DNAs or RNAs are prepared from the nucleicacid containing sample; a PCR (polymerase chain reaction) chamber wherethe DNAs or RNAs are amplified through PCR or RT-PCR; an array chamberwhere the amplified DNAs or cDNAs are hybridized to a capture probe; atrash chamber where the non-hybridized waste from the array chamber iscollected; and a plurality of chambers for storing a variety of enzymesand buffer solutions required for processes.
 14. The nucleic acid assaydevice of claim 13, being constructed as a lab-on-a-chip where thepreparation chamber, the PCR chamber, the trash chamber, channels, andholes are formed in a thin disk type body.
 15. The nucleic acid assaydevice of claim 14, wherein opening or closing of the valve holes of themicro valve apparatus at the start and end of each of the processes iscontrolled by the upper and lower electromagnets or by controlling thedirection in which power is applied to the upper and lower electrodeplates, and the fluid flow is induced by the centrifugal force whichoccurs as the disk type body is rotated.
 16. A nucleic acid assay methodin the nucleic acid assay device of claim 15, the method comprising: (a)injecting a nucleic acid containing sample into the preparation chambervia the sample injection unit; (b) preparing DNAs or RNAs from thenucleic acid containing sample; (c) opening a first hole between thepreparation chamber and the PCR chamber and rotating the nucleic acidassay device for a predetermined period of time, to transfer theprepared DNAs or RNAs to the PCR chamber; (d) closing the first hole,opening a second hole between a chamber which store enzymes and buffersolutions required for PCR and the POR chamber, and performing the PCRor RT-PCR to amplify the DNAs or RNAs; (e) after the PCR or RT-PCR hascompleted, closing the second hole, opening a third hole between the PCRchamber and the array chamber, and rotating the nucleic acid assaydevice for a predetermined period of time, to transfer the amplifiedDNAs or cDNAs to the array chamber; (f) closing the third hole, openinga fourth hole between a chamber which stores enzymes and buffersolutions required for hybridization and the array chamber, andperforming the hybridization; and (g) after the hybridization hascompleted, closing the fourth hole, opening a fifth hole between thearray chamber and the trash chamber, and rotating the nucleic acid assaydevice for a predetermined period of time, to collect the waste from thearray process within the trash chamber.
 17. A thin film type assaydevice in which fluid flow between chambers is controlled by a microvalve apparatus of claim 1 or 2, the device comprising: a sampleinjection unit via which a sample is injected; a preparation chamber; anarray chamber having capture probes; a trash chamber where the wastefrom the array chamber is collected; and a plurality of chambers forstoring a variety of enzymes or buffer solutions required for processes.18. A micro valve apparatus comprising: an upper substrate; anintermediate substrate; a lower substrate; channels as flow paths of afluid; the channels formed between the upper and lower substrates; avalve hole which interconnects the channels, the valve hole formed inthe intermediate substrate; chambers for storing a variety of assaybuffer and for chemical reactions; the chambers formed between the upperand lower substrates; an array chamber having capture probes fordetecting a small quantity of an analyte in a fluid; upper and lowerelectromagnets mounted on the top and bottom of exterior surfaces of therotatable disk; a rotatable disk in which the channels, the chambers,the array chamber and the valve hole are formed; wherein the fluid inthe channels flows from the center to edges of the rotatable disk bycentrifugal force caused by the rotation of the rotatable disk; and amicrobead which is moved upward or downward by magnetic force generatedby the upper and lower electromagnets, to open and close the valve hole,thereby controlling fluid flow and or quantity, wherein an upper channelconnecting a first chamber to the valve hole is formed recessed to afirst depth in the upper substrate, and a lower channel connecting asecond chamber to the valve hole is formed recessed to a second depth inthe lower substrate, wherein the first and the second chambers areinterconnected with each other through the channels when the valve holeis opened, wherein the upper substrate has a confining groove whichholds the microbead and prevents it from moving away when the rotatabledisk rotates.
 19. An apparatus, comprising: a rotatable disk having arotation axis and having channels carrying fluid via centrifugal forcetoward an outer edge of the disk, comprising: a first substrate having afirst fluid chamber and a first substrate outside surface; a secondsubstrate having a second fluid chamber and a second substrate outsidesurface; a third substrate in between the first and second substrates; afirst electromagnet formed on the first substrate outside surface; asecond electromagnet formed on the second substrate outside surface; avalve formed in the third substrate connecting the first and secondchambers in a direction parallel to the axis and perpendicular to theforce via an opening; a groove formed in the third substrate inalignment with the opening; and a cylindrical microbead positioned inthe valve and closing the opening by moving parallel to the axisresponsive to the electromagnets and being held in alignment with theopening by the groove.